Two-parameter fracture criterion (K_(ρ,c)-T_(ef,c)) based on notch fracture mechanics

摘要

A two-parameter fracture criterion has been proposed to predict fracture conditions of notched components. This criterion includes the critical notch stress intensity factor (K_(ρ,c), which represents fracture toughness of a material with a notch of radius p, and the effective T-stress. The effective T-stress T_(ef) has been estimated as the average value of the T-stress distribution in the region ahead of the notch tip at the effective distance X_(ef). These parameters were derived from the volumetric method of notch fracture mechanics. The results of numerical T_(ef,c)-stress estimation are compared to the T_(ef,c) -stress results obtained from experimental analysis. The material failure curve or master curve (K_(ρ,c)=f(T_(ef,c)) has been established as a result of the notched specimen tests. A large T_(ef,c) range was covered from -0.80 σ_Y to +0.19 σ_Y using SENT, CT, RT (roman tile) and DCB specimens. It was shown that the notch fracture toughness is a linear decreasing func tion of the T_(ef,c)-stress. The use of the material failure curve to predict fracture conditions was demonstrated on gas pipes with the surface notch.